Because of the extreme secrecy surrounding violations of the incest taboo, accurate data on the occurrence of incest are unobtainable. Nevertheless, all available sources indicate that father-daughter incest, in particular, is common in all social classes, and that the vast majority of cases escape detection by police and social agencies. As many as six per cent of all adult women may have a history of sexual abuse by adult relatives during childhood or adolescence. Existing studies, largely based on an unrepresentative sample of court cases, confound the effects of incest with the effects of punitive intervention. The proposed study is a detailed clinical investigation of adult women who report a history of a previously undetected incestuous relationship. The sample of 20 women will be selected from a population of outpatients in psychotherapy, after initial screening by their therapists. The group will be matched with 20 female outpatients who report a seductive father-daughter relationship which did not progress to overt incest. The groups will be compared in order to define: 1) a specific, identifiable family constellation associated with the development of overt incest, and 2) a characteristic clinical syndrome observed in the victims in later life. Results of the proposed study may have significance for the development of a preventive, non-punitive approach to the high-risk family, and for the development of more appropriate treatment for the victims of childhood sexual abuse.